Perkins 1104E Systems Operation Testing And Adjusting page 20

20
Systems Operation Section
Illustration 22
The timing wheel and the secondary speed/timing sensor
(32) Secondary speed/timing sensor
(33) Timing wheel
The ECU for the fuel injection pump is mounted on
the top of the pump. The ECU has a connection
to the engine ECM and a connection to the
speed/timing sensor. The ECU has a connection for
the two solenoid valves. The ECM functions as a
control computer. The ECU calculates the optimal
parameters from the ECM data. The fuel solenoid
actuates the valve accordingly.
The secondary speed/timing sensor in the fuel
injection pump determines the precise angular
position and the speed of the fuel injection pump
shaft. The timing wheel (23) is permanently
connected to the fuel injection pump shaft. The
secondary speed/timing sensor gets information from
the timing wheel. The sensor then sends electrical
impulses to the ECU. The ECU also uses the
information to determine the average speed of the
pump and momentary speed of the pump.
Note: The engine will not run if the secondary
speed/timing sensor fails.
The signal of the speed/timing sensor is constant.
Power command signals are routed over the CAN
data link from the engine ECM to the ECU on the fuel
injection pump.
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Illustration 23
Operating principle
(34) Angle of fuel delivery
(35) Lift of the cam
(36) Stroke
(37) Pulse for actuating the fuel solenoid
(38) Valve lift
(39) Angle of the speed/timing sensor
The amount of fuel is proportional to the stroke of
the piston. The effective stroke is proportional to the
angle of fuel delivery. A temperature compensation
takes place in the ECU. The compensation takes
place in order to inject the precise amount of fuel.
Shutoff
The engine shuts off by interrupting the fuel supply.
The engine Electronic Control Module (ECM)
specifies the amount of fuel. The fuel solenoid valve
is switched by the ECU on the fuel injection pump
to the zero fuel position.
SENR9977
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